I taped all the exterior sheathing joints (including at the foundation with high-performance air-sealing tapes). Then I applied a fully adhered vapor permeable airtight membrane to the entire exterior sheathing surface, and caulked the wall/roof joint, which also provided redundancy for the joint taping.

The general contractor applied a secondary bulk water shedding house wrap, a rain screen, and the finish cladding.

There were other things I did internally during the drywall/plasterboard stage also to minimize air movement through walls and ceilings.